linux-kernel - Re: [PATCH v1] Input: elants_i2c: Add Elan touchscreen support

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Date:	Thu, 20 Nov 2014 11:31:30 +0100
From:	Oliver Neukum <oneukum@...e.de>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	scott <scott.liu@....com.tw>, linux-kernel@...r.kernel.org,
	linux-input@...r.kernel.org,
	Vincent Wang <vincent.wang@....com.tw>,
	Jeff Chuang <jeff.chuang@....com.tw>,
	Benson Leung <bleung@...omium.org>,
	Benjamin Tissoires <benjamin.tissoires@...il.com>,
	Henrik Rydberg <rydberg@...omail.se>,
	David Herrmann <dh.herrmann@...il.com>
Subject: Re: [PATCH v1] Input: elants_i2c: Add Elan touchscreen support



> +static int elants_i2c_sw_reset(struct i2c_client *client)
> +{
> +       const u8 soft_rst_cmd[] = { 0x77, 0x77, 0x77, 0x77 };
> +       int error;
> +
> +       error = elants_i2c_send(client, soft_rst_cmd,
> +                               sizeof(soft_rst_cmd));
> +       if (error) {
> +               dev_err(&client->dev, "software reset failed: %d\n",
> error);
> +               return error;
> +       }
> +
> +       /*
> +        * We should wait at least 10 msec (but no more than 40)
> before
> +        * sending fastboot or IAP command to the device.
> +        */
> +       msleep(30);

If timing is critical in both ways, you should take our guarantee
if sufficient sleep. I suggest you sleep 11msecs.


> +static int elants_i2c_initialize(struct elants_data *ts)
> +{
> +       struct i2c_client *client = ts->client;
> +       int error, retry_cnt;
> +       const u8 hello_packet[] = { 0x55, 0x55, 0x55, 0x55 };
> +       const u8 recov_packet[] = { 0x55, 0x55, 0x80, 0x80 };
> +       u8 buf[HEADER_SIZE];
> +

Strictly speaking you should disable preemption here.

> +       for (retry_cnt = 0; retry_cnt < MAX_RETRIES; retry_cnt++) {
> +               error = elants_i2c_sw_reset(client);
> +               if (error) {
> +                       /* Continue initializing if it's the last try
> */
> +                       if (retry_cnt < MAX_RETRIES - 1)
> +                               continue;
> +               }

	Regards
		Oliver

-- 
Oliver Neukum <oneukum@...e.de>

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